Winds, Waves, Tides - Ocean Energy | Environmental News, Articles & Information | Global Warming News | EcoWorld - 2 views
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Can Already Cost Under $.06 per Kilowatt Hour * Pneumatic devices, such as the oscillating water column (OWC), use wave motion to compress and decompress air, and drive a turbine. * Float-based devices utilise a buoyant float moving with the waves, reacting against a sea bed anchor in order to harness energy. * Spillover devices utilise wave height to replenish a reservoir of seawater, which runs a turbine. * Raft-type devices use the relative motion of adjacent rafts or pontoons to harness wave energy. * Moving-body devices articulate in the water, inducing motion, which may be used to drive a hydraulic motor.
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Tidal stream devices extract energy from the diurnal flow of tidal currents (caused by the gravitational pull of the moon). Unlike wind and wave power, tidal streams offer entirely predictable output. However, as the lunar cycle is of around 25 hours’ duration, the timing of peak outputs differs by around an hour each day and tidal energy cannot be guaranteed at times of peak demand.
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However, several large grid-connected demonstration projects are expected to enter the water in the near future. Tidal stream is thus a few years behind wave energy.
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